For Want of a Nail
For want of a nail the shoe was lost.
For want of a shoe the horse was lost.
For want of a horse the rider was lost.
For want of a rider the message was lost.
For want of a message the battle was lost.
For want of a battle the kingdom was lost.
And all for the want of a horseshoe nail.
This old proverb emphasises how we can damage or entirely lose large or important things because of an overlooked small or apparently trivial thing. Exactly the same thing can happen in reverse. If you lose or destroy a big, obvious thing, you can lose everything just because of that. (The key expression here is trophic cascade. It's a pity that remembering this won't help when we play Trivial Pursuit.)
Most people are familiar with the return of wolves to Yellowstone resulting in a resurgence of other animals, trees and other plants. What many people don't realise is that the sum of those changes has altered the geography. The stronger tree and shrub growth has stabilised river banks making the course of the river different.
This video describes how all this comes together. https://www.youtube.com/watch?v=ysa5OBhXz-Q
However. I got this from a blog where the example of sharks is also used. I know there's a problem with removing large predatory fish from the oceans generally. But the example given here shows how you can totally destroy a specific locality (rather than have a dispersed effect over a large region).
Sharks exhibit a top down control on an ecosystem, if you remove them you disrupt the whole balance of nature. In 2005 a Mexican/US research team was able to study a particular area around a coral reef where sharks were hunted to local extinction to make it more tourist friendly. Seemed like a good idea, until the ecology of the coral suddenly all died within a year.
The study showed that
- the reef sharks preyed on octopus, and so kept the population quite low,
- when the sharks were taken away
- the octopus thrived
- and in turn killed off their own prey the urchin.
- this then caused the urchins competitor the star fish to grow in population because they had no competition for space
- and the star fish killed all the coral reef.
Looks like a real life version of the For want of a nail ... terrible consequences from loss or lack of a specific necessary thing.
I am pretty sure that "tourist friendly" meant lots of opportunity to dive and fish on the coral reef. Talk about cutting off your nose and spiting your face. There's another proverb about looking before you leap - it might have been a good idea to consult an ecologist or a coral reef expert before starting this whole thing.
How Wolves Change Rivers – A Lesson in BioDiversity | Climate Denial Crock of the Week
and the link to the shark story
AFRICAN SHARK ECO-CHARTERS Blog: What if Sharks became Extinct?